The mines of Mogok, Burma

Star ruby is a rare variety of ruby that exhibits asterism; a six-rayed star that shimmers over the surface of the stone when it is moved. The star effect is owed to aligned needle-like rutile inclusions. It is the rutile which is responsible for its silky shine. In rough form, ruby is dull and greasy, but when cut and polished its luster is comparable to fine diamond.